JPH1053849A - Method for preventing meandering of hot dipped steel strip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a hot dipped steel strip restaining the meandering, vibrating, warping, etc., of the steel strip and uniformizing coating weight. SOLUTION: At the time of squeezing the excess hot dipped metal stuck to the steel strip 1 drawn up from a hot dipping bath, electromagnetic force FR, FL to the strip width center direction according to the meandering quantity are acted to the steel strip 1 with electromagnets 13R, 13L for preventing the meandering arranged at the upper part of a coating weight control device to restrain the meandering of the steel strip 1. Further, the warping and the vibrating in the width direction of the steel strip 1 is restrained with the electromagnetic forces FU, FD of electromagnets 23U, 23D for positional control, arranged at the upper part of the electromagnets 13R, 13L, for preventing the meandering. To the steel strip warped in the strip width direction, plural electromagnets 23U, 23D for positional control are arranged along the width direction of the steel strip 1 and the electromagnetic force FU, FD generated with each electromagnet 23U, 23L for positional control is adjusted so that the distances between each electromagnet 23U, 23L for positional control and the steel strip surface 1 are equal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for preventing the meandering, vibration, etc. of a steel strip from affecting the fluctuation of the coating weight and for making the coating weight uniform.

[0002]

2. Description of the Related Art In a continuous hot-dip galvanizing line, as shown in FIG. 1, a steel strip 1, which is a raw plate for plating, is transferred to a reduction annealing furnace 2 maintained in a reducing atmosphere to activate the surface of the steel strip 1. After that, it is sent from the reduction annealing furnace 2 to the plating bath 4 via the snout 3. The steel strip 1 goes around the sink roll 5 immersed in the plating bath 4 and changes its traveling direction upward. Next, the steel strip 1 is sent out of the plating bath 4 via the support roll 6, and the amount of plating applied is adjusted by the gas wiping device 7 or the like. Then, the hot-dip plated steel strip 1 is transported to a post-process.

When the amount of plating is adjusted by the gas wiping device 7 or the like, if the steel strip 1 meanders or the distance from the gas wiping device 7 to the surface of the steel strip 1 changes, the steel strip 1 is sprayed on the steel strip surface. The effect of removing excess plating metal, such as gas pressure, fluctuates, and the amount of plating applied changes irregularly. Factors that cause the distance from the gas wiping device 7 to the surface of the steel strip 1 to fluctuate include vibration such as flapping of the steel strip 1 running at high speed, and warpage in the sheet width direction. Japanese Patent Application Laid-Open No. Sho 62-167163 discloses that a steel strip is suspended and supported by gas pressure, and a moving magnetic field whose strength changes in proportion to the amount of displacement in the width direction of the steel strip is applied to the steel strip from the plating bath. It is introduced to prevent meandering of the raised steel strip. JP-A-6-31329, JP-A-6-31330 and the like introduce a facility configuration in which fluid pads are arranged before and after a magnetic field generator that applies a moving magnetic field in the width direction to a steel strip.

[0004]

When the meandering of the steel strip is prevented by the conventional moving magnetic field, it is necessary to generate a large electromagnetic force in accordance with the amount of deviation in the width direction of the steel strip. However, the electromagnetic force not only eliminates the deviation in the width direction of the steel strip, but also works to suck the steel strip itself. Since the magnetic attraction force increases as the steel strip approaches the magnetic field generator, when the steel strip approaches one of the magnetic field generators located on both the front and back of the steel strip, a larger magnetic attraction force is generated, , The surface of the steel strip contacts the magnetic field generator or its peripheral equipment. As a result, defects such as surface flaws occur in the obtained plated steel strip.

[0005] The magnetic attraction of the steel strip can be prevented by increasing the pressure of the fluid ejected from the fluid pad, but the higher the attraction force, the higher the pressure is required. However, when a high-pressure fluid is sprayed on the surface of the steel strip, a loud impact sound is generated when the high-pressure fluid collides, and the working environment is significantly deteriorated. The present invention has been devised to solve such a problem, and instead of fluid pressure, the position of the steel strip is regulated by the electromagnetic force of the moving magnetic field, so that the steel strip pulled up from the hot-dip plating bath can be properly regulated. And to control the amount of plating with high precision without deteriorating the working environment.

[0006]

In order to achieve the object, the meandering prevention method according to the present invention, when squeezing surplus hot-dip metal adhered to a steel strip pulled up from a hot-dip plating bath, removes the amount of plating adhesion. A meandering prevention electromagnet placed above the control device applies electromagnetic force toward the center of the plate width according to the meandering amount to the steel strip to suppress meandering, and for position control placed above the meandering prevention electromagnet. The electromagnetic force of the electromagnet suppresses warping and vibration of the steel strip in the plate width direction. For a steel strip that is warped in the sheet width direction, a plurality of position control electromagnets are arranged along the width direction of the steel strip, and the distance between each position control electromagnet and the steel strip surface is the same. It is preferable to adjust the electromagnetic force generated by each position control electromagnet as described above.

In addition, the meandering preventing device of the present invention is provided at both ends in the width direction of the steel strip at a position above the coating weight control device for squeezing excess hot-dip metal deposited on the steel strip pulled up from the hot-dip plating bath. A pair of meandering preventing electromagnets arranged in the vicinity, a pair of meandering detection sensors arranged near both ends in the width direction of the steel strip and detecting both ends in the width direction, and a steel strip detected by the meandering detection sensor Is entered,
A meandering control device that calculates the current required for the electromagnetic force according to the meandering amount and outputs the current to the meandering preventing electromagnet; a position controlling electromagnet facing the front and back surfaces of the steel strip at a position above the meandering preventing electromagnet; The position sensor facing the front and back surfaces of the steel strip in the same positional relationship as the position control electromagnet in the band width direction, and the displacement of the steel strip detected by the position sensor are input, and the electromagnetic force according to the displacement is required. A meandering control device that calculates a current and outputs the calculated current to the position control electromagnet. A plurality of position control electromagnets facing the front and back surfaces of the steel strip are arranged along the width direction of the steel strip, and a plurality of position sensors are disposed in the steel strip width direction in the same positional relationship as the individual position control electromagnets. In a device facing both the front and back surfaces, warpage in the plate width direction can be corrected.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A meandering prevention device according to the present invention is provided on a downstream side of a coating weight control device with respect to a traveling line of a steel strip pulled up from a hot dip coating bath, and has a facility configuration shown in FIG. As the coating weight control device,
In addition to the gas wiping device 7 shown in FIG. 1, a magnetic field generating mechanism that narrows down the molten metal by electromagnetic force may be employed. In this meandering prevention device, a pair of meandering detection sensors 11 _out R, 11 _in R and 11 _out L, 11 _in L are arranged at both ends _in the width direction to detect the width direction ends of the steel strip 1.
The regular threading line of the steel strip 1 is the right-side meandering detection sensor 1
Between 1 _out R and 11 _in R and left meandering detection sensor 11
_The left and right ends in the plate width direction are set between _out L and 11 _in L. Sensors 11 _out R, 11 _in R and 11
_{For out} L and 11 _in L, for example, an optical sensor, an eddy current sensor, or the like is used.

The meandering detection sensors 11 _out R and 11 _out L are
When the steel strip 1 is running on the regular threading line, the steel strip 1
To detect the absence of. Meandering detection sensor 11 _in R, 11
_in L detects the presence of the steel strip 1 when the steel strip 1 is traveling on the regular threading line. Meandering detection sensor 11
_When the absence and presence of the steel strip 1 are detected at _out R, 11 _out L, and 11 _in R, 11 _in L, respectively, it is determined that the steel strip 1 is traveling along the regular threading line. . Steel strip 1
Meanders for some reason, and when the amount of displacement increases, the meandering detection sensor 11 _out R or 11 _out L
, The widthwise end of the steel strip 1 is detected, and the non-existence of the steel strip 1 is detected by the meandering detection sensor 11 _in L or 11 _in R on the other side. The detected deviation of the steel strip 1 is output to the meandering control devices 12R and 12L as a detection signal. Meandering control device 12
R and 12L calculate the required electromagnetic force according to the input displacement signal and output control signals to the meandering preventing electromagnets 13R and 13L. Meandering prevention electromagnets 13R, 13L
Generates a moving magnetic field having a strength corresponding to the supplied current, and applies a directional electromagnetic force FR or FL to the steel strip to cancel the deviation of the steel strip 1. As a result, the steel strip 1 is passed while the meandering is canceled.

According to this method, even when the steel strip 1 is slightly displaced, the electromagnetic force FR or FL acts so as to cancel the deviation. Therefore, the required electromagnetic force FR or FL
, And small electromagnets 13R and 13L can be used. Further, the force for attracting the steel strip 1 in the direction of the electromagnets 13R and 13L is also reduced. However, the electromagnets 13R, 13L that generate the electromagnetic force FR or FL for canceling the meandering prevention
As shown in FIG. 2 (a), a pair is arranged on both sides of the steel strip 1. Therefore, if the running steel strip 1 is displaced in the front and back directions, such as flapping, the electromagnetic force of the electromagnets 13R and 13L on the side closer to the steel strip 1 acts on the steel strip 1 greatly. An attempt is made to move closer to the electromagnets 13R and 13L. In the present invention, the displacement of the steel strip 1 in the front and back directions is detected by the position sensors 21, 21,. A plurality of position sensors 21, 21, ... are arranged at equal intervals along the width direction of the steel strip 1. The surface position information of the steel strip 1 detected by the position sensors 21, 21,...
It is output to the position control device 22. The position control device 22 calculates the required electromagnetic force according to the input surface position information of the steel strip 1 and outputs the calculated electromagnetic force to the position control electromagnets 23U and 23D arranged on both sides of the steel strip. The position control electromagnets 23U and 23D are electromagnets that generate a moving magnetic field having an intensity corresponding to the supplied current.
.. Are arranged at equal intervals along the width direction of the steel strip 1.

Each of the electromagnets 23U, 23D generates a moving magnetic field having an intensity proportional to the displacement of the steel strip 1 detected by the position sensors 21, 21,..., And applies electromagnetic forces FU, FD to the steel strip 1. Let it. That is, when the steel strip 1 is separated from one of the electromagnets 23U or 23D due to the flapping during traveling, a large displacement is detected by the position sensors 21, 21,... According to the separated state. Therefore, when an electromagnetic force FU or FD proportional to the displacement is applied to the steel strip 1, the steel strip 1 is pulled toward the electromagnet 23U or 23D by the electromagnetic force FU or FD, and the displacement is corrected. Therefore, the electromagnet 1
The steel strip 1 does not come into contact with the 3R, 13L, 23R, 23L or peripheral equipment, and the generation of surface defects on the plated steel strip is prevented. At this time, the electromagnetic forces of the plurality of electromagnets 23U and 23D arranged along the plate width direction are combined to form electromagnetic forces FU and FD.
Even if a small electromagnet is used for 23D, the required magnitude of electromagnetic force FU, FD can be obtained.

The steel strip 1 pulled up from the plating bath is often along the width direction (hereinafter referred to as C warpage).
The C warpage causes the steel strip 1 to be attracted by one of the electromagnets 23U or 23D in the same manner as the displacement due to flapping or the like. According to the present invention, a plurality of electromagnets 23U,
By adjusting the magnitudes of the electromagnetic forces FU and FD generated by 23D, the trouble due to the C warpage is also eliminated. For example, when the steel strip 1 is C-warped as shown by a solid line in FIG.
U, 23U, the electromagnets 23D, 23D
To reduce the electromagnetic force. In addition, the electromagnetic force of the electromagnets 23U, 23U facing the central portion in the plate width direction is reduced,
Increase the electromagnetic force of 3D and 23D. Thus, the steel strip 1 is corrected from the shape C ₀ that C warp flat shape C ₁ shown in FIG. 3 by a two-dot chain line. Of course, the steel strip 1 whose shape has been corrected is not attracted to the meandering preventing electromagnets 13R and 13L and the position controlling electromagnets 23R and 23L.
The drawing action of the hot-dip coated metal by the coating weight control device such as the gas wiping device 7 is made uniform in the width direction of the steel strip 1. As a result, a hot-dip galvanized steel strip having a uniform coating weight can be obtained. Further, since the C warpage is also corrected, a hot-dip coated steel strip having no thermal distortion is obtained.

[0013]

EXAMPLE A normal steel strip having a thickness of 0.8 mm and a width of 1200 mm was introduced at a rate of 100 m / min into a Zn plating bath at a temperature of 460 ° C., and excess molten steel adhered to the steel strip pulled up from the Zn plating bath. The plated metal was squeezed out by gas wiping, and the amount of plating was adjusted to 90 g / m ² . The meandering of the steel strip was regulated by the electromagnetic force of the electromagnets 13R and 13L disposed 200 mm above the gas wiping device 7 (FIG. 1). The positions of the steel strips are determined by the electromagnets 23U, 23U which are arranged 100 mm above the electromagnets 13R, 13L.
Controlled by D electromagnetic force. In each of the electromagnets 13R, 13L and 23U, 23D, the distance to the steel strip was set to 10 mm. As the meandering preventing electromagnets 13R and 13L, electromagnets having a height of 100 mm and a width of 400 mm were used, and a three-phase alternating current of 600 Hz was supplied. The supply current was adjusted in the range of 0 to 150 A corresponding to 1 according to the meandering amount of the steel strip.

As the position controlling electromagnets 23U and 23D, five electromagnets having a diameter of 100 mm and 2,000 turns were arranged at equal intervals in the width direction of the steel strip (a total of ten electromagnets on both sides). A direct current of 50 to 200 A was supplied to each of the electromagnets 23U and 23D according to the vibration of the steel strip and the C warpage. When hot-dip plating was performed under these conditions,
Meandering and flapping of the steel strip were suppressed during plating. Also,
Variation related to the plate width direction of the basis weight had been reduced to a range of ± 10 g / m ² with respect to the target basis weight 90 g / m ^2. The meandering amount of the steel strip was also suppressed to within ± 3 mm. This is because the adjusted electromagnetic forces FR, FL and FU, F
D is a result of efficiently suppressing meandering, flapping, and C warpage, and making the wiping action uniform in the sheet width direction.
On the other hand, when the electromagnetic forces FU and FD for correcting the C warpage were not controlled, it was the limit to suppress the variation in the coating amount in the plate width direction to ± 20 g / m ² . Further, when the electromagnetic force FR, FL for preventing meandering was not applied, the steel strip meandered as large as ± 10 mm, and it was not possible to control the amount of plating under stable conditions.

[0015]

As described above, in the present invention, when the excess hot-dip coated metal is squeezed out of the steel strip pulled up from the hot-dip plating bath to adjust the coating weight,
The electromagnetic force acts to cancel the meandering of the steel strip, and the electromagnetic force acts toward the surface of the steel strip so that the steel strip travels along the regular threading line. As a result, the steel strip is prevented from approaching one of the electromagnets, and the surface of the plated steel strip does not have any flaws caused by contact with the electromagnet or its peripheral devices. A hot-dip coated steel strip having a uniform amount is produced. Further, since the electromagnet to be used can be small, the load on the equipment is small, and the hot-dip plating can be performed under a much quieter working environment than the conventional method.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram for controlling the coating weight of a hot-dip plating facility.

FIG. 2 is a view of the meandering prevention device according to the present invention when viewed in the width direction (a) of the steel strip and in the thickness direction (b).

FIG. 3 is an explanatory view of C warpage correction.

[Explanation of symbols]

1: Steel strip 2: Reduction annealing furnace 3: Snout 4:
Plating bath 5: Sink roll 6: Support roll 7: Gas wiping device 11 _out R, 11 _in R, 11 _out L, 11 _in L: meandering detection sensor 12R, 12L: meandering control device 13R, 13L:
Meandering prevention electromagnets 21, 21: Position sensor 22: Position control device 23U, 23D: Position control electromagnet FR, FL: Electromagnetic force for regulating the meandering of the steel strip FU, FD: Direction perpendicular to the steel strip surface Electromagnetic force that regulates displacement of steel strip S ₀ : Profile of steel strip with C warpage S ₁ : Profile of steel strip whose shape has been corrected

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazunari Nakamoto 1 Tsurumachi, Amagasaki-shi, Hyogo Prefecture Nisshin Steel Co., Ltd.

Claims (4)

[Claims] When a surplus hot-dip metal deposited on a steel strip pulled up from a hot-dip bath is squeezed out, a meandering-preventing electromagnet disposed above a plating-adhesion-amount controller controls a sheet width according to the meandering amount. The meandering electromagnetic force acts on the steel strip to suppress meandering, and the electromagnetic force of the position control electromagnet placed above the meandering prevention electromagnet suppresses warpage and vibration in the steel strip width direction. A meandering preventing method for a hot-dip steel strip. 2. A plurality of position control electromagnets are arranged along the width direction of the steel strip, and are generated by each position control electromagnet such that the distance between each position control electromagnet and the surface of the steel strip is the same. The method for preventing meandering of a hot-dip galvanized steel strip according to claim 1, wherein the electromagnetic force is adjusted. 3. A pair of each pair disposed in the vicinity of both ends in the width direction of the steel strip at a position above the coating weight control device for squeezing excess hot-dip metal adhered to the steel strip pulled up from the hot-dip plating bath. A meandering preventing electromagnet, a pair of meandering detection sensors arranged near both ends in the width direction of the steel strip and detecting both ends in the width direction, and a meandering amount of the steel strip detected by the meandering detection sensor are input. A meandering control device that calculates the current required for the electromagnetic force according to the amount and outputs it to the meandering prevention electromagnet; a position control electromagnet facing the front and back surfaces of the steel strip at a position above the meandering prevention electromagnet; A position sensor facing the front and back surfaces of the steel strip in the same direction as the position control electromagnet in the width direction, and the displacement of the steel strip detected by the position sensor are input, and the current required for the electromagnetic force according to the displacement is input For position control A meandering prevention device for a hot-dip galvanized steel strip, comprising a meandering control device that outputs to an electromagnet. 4. A plurality of position controlling electromagnets facing the front and back surfaces of the steel strip are arranged along the width direction of the steel strip, and a plurality of position control electromagnets are arranged in the steel strip width direction in the same positional relationship as the individual position control electromagnets. The meandering preventing device for a hot-dip coated steel strip according to claim 3, wherein the sensor is opposed to both front and back surfaces of the steel strip.